If you going to drop it, 225/40/18 will definitely scrub, especially the rear arc. even after rolling the cutter. Mine i had to get it replace by 215/35/18 as none of the mention above could solve.
Yeah I think this topic has been covered has been covered before, but anyway my wheels are 18X7 with 215/34. The springs have been dropped by 50mm with rolled rear guard , bcos I used to carry it with 225/40 and it scrub.
If this is a multiple choice, then i'll pick C. But I also think it's B and C
I have adjusted C on mine, by myself, but didn't know that B can be adjust.
I can tell u that it has no problem changing gear know on high revs.
If u'r exhaust run across and comes out on the left hand side then there are many option for u to choose. There are: trd, c-one, fujitsubo and hks to choose from. They are properly designed mufflers, so u shouldn't have problem with gaining power.